if you melt the pile of powder, it will start to smoke. blow the first vapors out of the pipe and let the powder recristalize into a single crystal. also if you want to take a bowl with you, you just melt some and recristalize in the bowl, now swim
's got a bowl of shard in his pipe that can be disposed of quickly.
to sum it up, you throw away the first round of vapors. you only need to heat to liquid, nothing more, let cool.